Unfortuately it's not only the gtk-breeze theme that breaks Gimp's UI, the problems also appears with Adwaita theme, but much less prominent.
So maybe gtk-breeze triggers the issue more intensivly, but the issue seems to be more general and GTK related, because in the meantime I noticed, that other GTK programs are also slightly effected. ** Changed in: breeze-gtk (Ubuntu) Status: New => Invalid -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1971561 Title: Colorful rectangles are added incorrectly by breeze-gtk theme To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/breeze-gtk/+bug/1971561/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs